The present invention relates to power driven conveyors and more particularly, to a system and method for conveying objects from one power driven conveyor to another power driven conveyor. The system and method can be used for any object moving on a conveyor belt, but will be discussed in the context of tortillas.
Tortillas can be removed from one conveyor belt and transported to another by manual labor, but this is not commercially acceptable, because labor is relatively expensive and workers have difficulty removing the hot tortillas at the speed necessary for large volume commercial production. Workers also create non-uniform spacing between tortillas and damage the tortillas, because of the tortillas' tendency to adhere to the conveyor belt surface. In order to efficiently process tortillas there is a need to automate removal and transport.
Particularly in the commercial baking industry, the use of conveyors for the movement of tortillas, and other food objects, is generally well known. Examples of conveyors include, but are not limited to, an endless belt conveyor driven around two or more axles. Typically, one axle is powered and the others are non-powered or idler axles. In the food industry in particular, it is common to construct multi-tiered conveyors, of two or more paired conveyors traveling in opposing clockwise and counterclockwise directions, and it is necessary to transfer objects between the successive levels of such multi-tiered conveyor systems.
As shown in FIG. 1, one solution used with tortilla manufacturing is to place arcuate transfer guides at the ends of each pair of belts where the tortillas are transferred from an upper belt to the next lower belt. The guides provide a stationary curved transfer surface extending between the respective exit and entry ends of the pair of belts upon and along which the tortillas discharging off the exit end of the upper belt are guided to slide downwardly to the entry end of the next lower belt. Examples of such transfer guides are found in U.S. Pat. No. 5,392,696 to Navarro, et al for a “Tortilla transfer guide and method for transferring tortillas”; U.S. Pat. No. 4,715,272 to Mendoza for a “System for preparing tortillas” and U.S. Pat. No. 2,709,412 to Eagerman for an “Automatic baking oven.”
Generally, an automated apparatus employing multi-tiered conveyors operates at high speeds to produce more product in less time. The high speed of the apparatus requires that product flow not be slowed down at any point. Additionally, in the event of a jam up, the affected area should be easy to clean without production being affected. A transfer system should provide as little resistance as possible so as not to hinder product flow. Preferably a system should be incorporated to permit fast and easy removal of jams.
With baked tortilla products, undercooked or unpressed dough pieces may be present on the conveyor. Because these products are typically sticky, or too large to pass through the gravity transfer guide, they become stuck to the guide, or stuck in the area between the conveyor and the guide. Limiting the time spent on the guide to a minimum reduces the likelihood of the product being becoming stuck.
In addition, as the tortilla transfers from the upper conveyor to the transfer guide it increases in speed, and as it enters onto the lower conveyor it may slide forward having a longitudinal speed relative to the belt speed of the lower conveyor. This results in uneven longitudinal spacing between the tortillas, which is undesirable. In some instances, overlapping may even occur.
Prior art systems do not meet these needs, and may even exacerbate longitudinal spacing problems. For example, in one prior art system an attempt is made to guide or move the dough piece to correct lateral displacement. However, this system only slows the longitudinal forward travel of the piece, resulting in uneven longitudinal speeds and spacing of the food products. The need for maintaining proper spacing rather then correcting misplacement is more beneficial for high speed production lines.
What is needed is a transfer system and method which minimizes the time the product spends on the guide, preferably maintains longitudinal spacing of product after transfer, and preferably permits easy clearing of trapped pieces.